From patchwork Tue Jun 15 14:13:24 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yongji Xie X-Patchwork-Id: 12321923 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EA839C48BDF for ; Tue, 15 Jun 2021 14:17:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C91C761481 for ; Tue, 15 Jun 2021 14:17:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231150AbhFOOTF (ORCPT ); Tue, 15 Jun 2021 10:19:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36798 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230410AbhFOORb (ORCPT ); Tue, 15 Jun 2021 10:17:31 -0400 Received: from mail-pg1-x534.google.com (mail-pg1-x534.google.com [IPv6:2607:f8b0:4864:20::534]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5AF38C061151 for ; Tue, 15 Jun 2021 07:14:07 -0700 (PDT) Received: by mail-pg1-x534.google.com with SMTP id w31so9058115pga.6 for ; Tue, 15 Jun 2021 07:14:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=b7apvPbQfTG1FYg2uNsocmvMG/QdC7c4RuzNmrGKxtc=; b=teEC3X5118RCoqRjDpVinxrBxb/ZnCm6ryA5hTE///DNJNJIJ7ry41IlzLM/WQ5RZi 5rM29Gvy1WbJsWL0k3ucFdrxybEvdyBmK744/4SAfTdXMBCd9dtjzdV6h4lNYp1H3YAe RaY/wxthVmrWQYX778EfdTQbqgDLnqWYzbbAUF0xXFFqFVkE4KxZ564GQjL0iwdHK9zR QipmY/L7g/sua/MKoU4gAbpjYDQ8XMk0LrElfchchmEY96U4NRRm7211KAJCMtvD/tLG 2zK0nUfsHKDTzh/XdBfdvD4OZrzHRQtNECYGSoQtBcAELiDzP1QZt2UELiaroy3e2M1k QF/Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=b7apvPbQfTG1FYg2uNsocmvMG/QdC7c4RuzNmrGKxtc=; b=fNFzMxS+UN7ggQEoYKVJC3WvL0s7JGMP3eOZ6zzUUAVPgdi6rf4agO1wBiYWjon/VV ZOF3qvKzMlhu+LMKGYb8Bo5KzqFcRGRj2fnUGAaWwwhdmpXMWK6Sxe1dktt1duFKjufG q89W2ClXEmmbzUfxYiSA5L9zHDSAsbN0YzCOG57wUp+Ncq53yWwwQPmn/8j0SHO8JdD7 3Jrni78lhZOk70idZIecsx7Aw6byPQ24pPQa3yyXhhnLDoL2sXZjluJGvk262SCo+X00 v74EKcVCQsDY+pp9T8W1BVvpu//7FInPk0fBmb1dmVZJ78NwsA32PLjN4JK/1vJiepuo wmMg== X-Gm-Message-State: AOAM532ylJhH1nEnx6lvBjBDXicNTM1Shu/uNqAaCB7YPBJ922GZTocv A244ORn+QpNHG80eVsStXzvO X-Google-Smtp-Source: ABdhPJzJT+1d1E8F4L3uwEMXEuWS3/RAonqjFcnOvR03YvpVA7eJh794mNzTaDsLprM6LBC/PxXhrA== X-Received: by 2002:a63:9302:: with SMTP id b2mr3039614pge.277.1623766446912; Tue, 15 Jun 2021 07:14:06 -0700 (PDT) Received: from localhost ([139.177.225.241]) by smtp.gmail.com with ESMTPSA id d8sm16097026pfq.198.2021.06.15.07.14.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 15 Jun 2021 07:14:06 -0700 (PDT) From: Xie Yongji To: mst@redhat.com, jasowang@redhat.com, stefanha@redhat.com, sgarzare@redhat.com, parav@nvidia.com, hch@infradead.org, christian.brauner@canonical.com, rdunlap@infradead.org, willy@infradead.org, viro@zeniv.linux.org.uk, axboe@kernel.dk, bcrl@kvack.org, corbet@lwn.net, mika.penttila@nextfour.com, dan.carpenter@oracle.com, joro@8bytes.org, gregkh@linuxfoundation.org Cc: songmuchun@bytedance.com, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, kvm@vger.kernel.org, linux-fsdevel@vger.kernel.org, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: [PATCH v8 03/10] eventfd: Increase the recursion depth of eventfd_signal() Date: Tue, 15 Jun 2021 22:13:24 +0800 Message-Id: <20210615141331.407-4-xieyongji@bytedance.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210615141331.407-1-xieyongji@bytedance.com> References: <20210615141331.407-1-xieyongji@bytedance.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Increase the recursion depth of eventfd_signal() to 1. This is the maximum recursion depth we have found so far, which can be triggered with the following call chain: kvm_io_bus_write [kvm] --> ioeventfd_write [kvm] --> eventfd_signal [eventfd] --> vhost_poll_wakeup [vhost] --> vduse_vdpa_kick_vq [vduse] --> eventfd_signal [eventfd] Signed-off-by: Xie Yongji Acked-by: Jason Wang --- fs/eventfd.c | 2 +- include/linux/eventfd.h | 5 ++++- 2 files changed, 5 insertions(+), 2 deletions(-) diff --git a/fs/eventfd.c b/fs/eventfd.c index e265b6dd4f34..cc7cd1dbedd3 100644 --- a/fs/eventfd.c +++ b/fs/eventfd.c @@ -71,7 +71,7 @@ __u64 eventfd_signal(struct eventfd_ctx *ctx, __u64 n) * it returns true, the eventfd_signal() call should be deferred to a * safe context. */ - if (WARN_ON_ONCE(this_cpu_read(eventfd_wake_count))) + if (WARN_ON_ONCE(this_cpu_read(eventfd_wake_count) > EFD_WAKE_DEPTH)) return 0; spin_lock_irqsave(&ctx->wqh.lock, flags); diff --git a/include/linux/eventfd.h b/include/linux/eventfd.h index fa0a524baed0..886d99cd38ef 100644 --- a/include/linux/eventfd.h +++ b/include/linux/eventfd.h @@ -29,6 +29,9 @@ #define EFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK) #define EFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS | EFD_SEMAPHORE) +/* Maximum recursion depth */ +#define EFD_WAKE_DEPTH 1 + struct eventfd_ctx; struct file; @@ -47,7 +50,7 @@ DECLARE_PER_CPU(int, eventfd_wake_count); static inline bool eventfd_signal_count(void) { - return this_cpu_read(eventfd_wake_count); + return this_cpu_read(eventfd_wake_count) > EFD_WAKE_DEPTH; } #else /* CONFIG_EVENTFD */